This invention relates to fluorescent lamp ballasts and, in particular, to a fluorescent lamp ballast that is light in weight compared to an inductive ballast and conserves energy.
Despite their widespread use, incandescent lamps are relatively inefficient, with a 100 watt lamp producing about 16 lumens per watt of input power and having a relatively short service life as compared to other light sources. Fluorescent lamps, which have efficiencies as high as 80 lumens per watt, provide an attractive alternative to incandescent lighting. Increased residential use of fluorescent illumination, with attendant savings of energy, can be achieved from the development of fluorescent lamp systems which are directly compatible with existing sockets. However, lamps of this variety generally require a lightweight ballast if it is desired to retrofit fluorescent lamp systems in existing incandescent sockets.
One such lightweight ballast is disclosed in U.S. Pat. No. 2,356,369 dated Aug. 22, 1944, issued to David W. Abernathy. The Abernathy Patent discloses a fluorescent lighting circuit that utilizes a purely resistive ballast during normal operation of the fluorescent lighting tube. The use of a resistive ballast of this type is less expensive than an inductive ballast and is lighter in weight.
Another resistively ballasted fluorescent lamp is disclosed in U.S. Pat. No. 3,996,493 dated Dec. 7, 1976, issued to Davenport et al. The Davenport Patent discloses an integral self-contained fluorescent lamp unit comprising an elongated lamp and an elongated ballast resistor carried in an outwardly extending housing member positioned alongside the lamp.
A problem is often encountered with resistively ballasted fluorescent lighting systems in that the resistor consumes excessive power and, in addition, it is often difficult to dissipate the excessive heat generated by the resistor.